Mya Nelson
Girls who are overweight as young children and teens may face increased risk for colorectal cancer decades later, regardless of what they weigh as adults, suggests a new study published in Cancer Epidemiology Biomarkers and Prevention. The study is partially funded by AICR. 
In an unexpected finding, the same link for overweight boys and adult colorectal cancer was not found.
While the link between overweight adult and higher risk of developing colorectal cancer is clear — for both women and men — the role of excess body fat as a child is an emerging area of research.
For the study, researchers pulled data from almost 110,000 people who were part of two large and long-term population studies. One included only women, the Nurses’ Health Study, and the other men, the Health Professionals Follow-up study.
Back in 1988, everyone had picked from a set of nine body shapes on what they looked like at ages 5, 10, 20, 30, and 40, along with their current age. Then everyone regularly answered questionnaires about their weight, activity, diet and other lifestyle habits.
After an average of 22 years, 2,100 people had developed colorectal cancer.
After adjusting for weight, the study found that women who were overweight as young girls had a 27 percent higher risk of colorectal cancer compared to those who were most lean at those ages. Women who were overweight as adolescents had about the same level of increased risk. There was no significant association in men.
Disentangling the independent link between being overweight and youth and as an adult is challenging, write the authors. But this study does confirm previous research. Excess body fat can cause high levels of insulin and insulin-like hormones, which studies suggest increases risk of colorectal cancer.
No link appearing in men could be do to faulty recall among men, the authors note. But it also may be that early life body fatness has a different effect on each sex when it comes to colorectal cancer risk. Adult weight gain and its effects may play more of a role in colorectal cancer for men.
More research is needed, but this is just one more reason why it’s important for children to be at a healthy weight.
Colorectal cancer is only one cancer linked to early life factors. We’ve written about early life and later breast cancer risk before.
The study was supported by the American Institute for Cancer Research and National Institutes of Health.
